1. Field of the Invention
The present invention relates to a weft insertion control method and apparatus for selecting one of a plurality of wefts in accordance with a weft color selection pattern for insertion into a multi-color fabric being woven by a multi-color jet loom.
2. Description of the Prior Art
In a multi-color loom, in which a single pressurized fluid supply system is provided for weft insertion auxiliary nozzles, the pressure of jets produced by the weft insertion auxiliary nozzles is generally so set as to conform to the lowest running speed of a weft among those of different types. This can be explained by the fact that in case the jet pressure of the auxiliary nozzles is set in accordance with a weft having a higher running speed, the period for the tip of the weft having a lower running speed to reach the end position will be delayed, causing a faulty weft insertion. However, even in cases where the jet pressure is set in accordance with the weft of the lowest running speed, the weft which can be fed at an intrinsically higher speed will then tend to run at a speed abnormally higher than the desired speed, resulting in yarn breakage and wasteful consumption of pressurized fluid.
Weft insertion controlling systems which tackle the above-mentioned problem are disclosed in JP-A-58-126344 (Japanese Patent Application Laid-Open No. 126344/1983) corresponding to U.S. Pat. No. 4,534,387, JP-A-59-125942 and JP-A-59-130348 corresponding to U.S. Pat. No. 4,646,791. More particularly, in the weft insertion control systems disclosed in JP-A-58-126344 and JP-A-59-125942, a plurality of pressurized fluid supply systems of different pressures are provided in parallel to each weft inserting auxiliary nozzle, wherein one of the plurality of pressurized fluid supply systems is selectively connected to the weft inserting auxiliary nozzles depending on the type of weft to be inserted.
In the weft insertion control apparatus disclosed in JP-A-59-130348, a group of weft inserting auxiliary nozzles is provided for each type of weft and adapted to be connectable to an associated one of a plurality of pressurized fluid supply systems of different pressures, wherein one of the plural weft inserting auxiliary nozzle groups is selected for use from the plural groups of the weft inserting auxiliary nozzles in accordance with the type of weft to be inserted.
However, the weft insertion control apparatus of JP-A-59-125942 suffers from problems in that the space for installation is increased and the piping arrangement is complicated because a pressurized fluid supply tank must be provided for each type of weft in order to constitute a plurality of pressurized fluid supply systems. On the other hand, the weft insertion control apparatus of JP-A-58-126344 is disadvantageous in that increases in the cost involved as well as complicated piping are inevitable because a plurality of pressure control valves are interposed in parallel between the pressurized fluid supply tanks and the weft inserting auxiliary nozzles in order to constitute a plurality of pressurized fluid supply systems.
In the weft insertion control apparatus of JP-A-59-130348, the problems mentioned above are more serious, because of the increase in the number of weft inserting auxiliary nozzles.